Apparatus for cleaning grinding wheels



Feb. 2, 1965 D. s. GIARDINI ETAL 3,167,393

APPARATUS FOR CLEANING GRINDING WHEELS Filed NOV. 5, 1962 INVENTORS DANT GIARD 8 RICHA N. RON

BY WMLJW THEIR ATTORNEY United States Patent Office 3,167,893 Patented. Feb. 2, 1965 5 167 893 APPARATUS FOR cLEANiNG GRINDING wnnnps Dante S. Giardini and Richard N. Roney, Dayton, Ohio, assignors to The Sheffield Corporation, Dayton, Ohio, a

corporation of Delaware Filed Nov. 5, 1962, Ser. No. 235,484 4 Claims. (Cl. 51262) This invention relates to grinding wheels and more particularly to the cleaning of wheels.

One object of the invention is the provision of an apparatus for effectively cleaning the operative surface of a grinding wheel during operation to maintain the grinding wheel free of loading.

Another object of the invention is the provision of cleaning apparatus for grinding wheels in which there is provision for directing a small jet of cleaning liquid against the cutting surface, the jet being of extremely high velocity and of such character as to continually clean off work particles that would otherwise accumulate on the cutting surface.

Another object of the invention is the provision of a device of the character mentioned in which the jet is moved back and forth across the cutting surface of the grinding wheel. 7

Other objects and advantages of the invention will be apparent from the following description, the appended claims, and the accompanying drawing, in which,

FIG. 1 is a perspective view of the grinding machine embodying and for carrying out the present invention,

FIG. 2 is an enlarged section on the line 2-2 of FIG. 1.

Present machine shop practice during grinding operations is to supply a large volume of coolant oil on a grinding wheel and workpiece at the grinding zone to serve as a coolant and wash away loose particles of foreign matter in the grinding area. After some period of use the grinding wheel becomes loaded with particles from the workpiece and after an excessive build-up of loading the grinding wheel is redressed, as for example by a metal crusher to impart a desired form on the grinding wheel.

In accordance with the present invention, the cutting surface of the wheel is cleaned or kept clean continuously by applying a jet of cleaning liquid of small size but of sufiiciently high velocity against the cutting surface of the wheel to keep it clean of loading. An effective cleaning action is obtained over the entire cutting surface of the grinding wheel as the jet of cleaning liquid is reciprocating slowly across. the width of the grinding surface while the wheel is rotating at a fast speed. The jet of cleaning liquid is held in close proximity to the cutting surface of the grinding wheel. One jet moving directly toward the cutting surface of the grinding wheel or two or more jets spaced apart or at different angles may be used. The high velocity jet is preferably located at a point remote from the grinding zone so that cleaning liquid and air mist created as the high velocity jet contacts the grinding wheel can be readily withdrawn. It is also preferable to filter and use as cleaning liquid the same liquid that is used in the main coolant system.

The size of the orifice used is such that extremely large flows of liquid are not present. The jet is of sufliciently high velocity to maintain the wheel free of loading under very extended periods of operation where the wheel is used to grind the ordinary types of materials ground by the grinding machine on which the wheel is used. The grinding wheel is thus kept continuously in an efiicient cutting condition over extended periods of use and with a resultant cooler grinding operation that provides for increased precision of the ground form.

The high velocity jet is produced by pressurizing the cleaning liquid and ejecting it against the cutting surface of the grinding wheel through the small orifice at pressures in excess of about 1,000 pounds per square inch. With a substantially smaller pressure than about 1,000 pounds per square inch an effective cleaning action is not produced on wheels used normally in machine shop operations on even the softer variety of metals. Using pressures in excess of the value just mentioned produces effective cleaning for relatively low hardness materials such as aluminum or the like; although pressures of the order of several thousand pounds per square inch should be used to keep the wheel free of loading for many metals. For the variety of materials normally operated on in most machine shops, it has been determined that pressures of about 4,000 to 10,000 pounds per square inch satisfy cleaning requirements with the higher pressures employed, even up to 20,000 pounds per square inch or more in grinding workpieces of a material of very high tensile strength. Extremely high pressures of course introduce safety considerations. In this regard note that in the illustrated embodiment the cleaning jet nozzle is located remotely from the grinding zone at a location generally 180 degrees therefrom and hence away from the proximity of operating personnel.

The cleaning liquid employed may be a coolant oil having a viscosity index, for example, of the order of 225 SSU, or the liquid may be water with a rust inhibitor or a water soluble oil. With 10,000 pounds per square inch pressure and with an orifice size of .010 about one quart of cleaning oil is provided per minute and at a velocity of about 1,000 feet per second or more. The cleaning liquid is driven into the interstices of the grinding wheel by the high velocity jet and as it emits from the wheel at the grinding zone during rotation it has the added advantage of tending to quench sparking. Since a clean wheel also produces less sparking than a loaded wheel the result is a substantially cooler workpiece and the production of a greater number of finished parts to a required precision.

The orifice size employed is preferably of the order of about of an inch in diameter. If the diameter is substantially less than .006 there is liability of clogging. An orifice size of .015 inch in diameter has proved quite satisfactory. Very large orifices are not feasible because of the great power requirements to maintain the high pressure and the extreme difficulty of collecting and handling the great quantity of liquid that would be ejected against the grinding wheel and the great volume of liquid and air mist that would result.

One form of apparatus for carrying out the invention is illustrated in the drawing showing a grinding machine generally designated 10 having a power operated grinding wheel 11 arranged to grind workpieces such as 12 held on centers 13. The grinding wheel may have a form of any suitable character to grind a desired contour as the grinding wheel is fed into the work. This form may be imparted in any conventional manner as for example by operating the grinding wheel in peripheral pressure contact with a metal crusher which imparts the form desired. As in a conventional grinding machine, coolant oil flows on to the work and wheel. The coolant oil may be conveyed through a conduit 14 from a supply tank 15 and flows at very low pressure from a pump 16. This coolant flow is in large volume. The coolant is collected by a collecting pan or sump arrangement as shown at 17 and returns through the return conduit 18 to the supply tank.

In accordance with the present invention, some of the coolant oil may be used as the cleaning liquid. It may be withdrawn from the tank through a conduit 19, passed through a filter 20 to a high pressure pump 21 which has its discharge pressure controlled by an adjustable relief valve 37. The oil from the pump 21 passes through a conduit 22.having a flexible portion or coil 23. Conduit 22 is guided for movement in a support 24 and passes through an opening at 25 in a shroud 26 around the grinding wheel. The end of the conduit is provided with an orifice at 27 arranged closely adjacent to' the periphery of the grinding wheel and directed generally toward the Wheel. The oil supplied. from the high pressure pump passes through the orifice which is very small in size soth at with the high pressure supply a high velocity jet of'cleaning oil is directed forceably against the grinding wheel.

The jet may be directed normally against the I cutting surfacekof the grinding wheel or-at. 7

suitable angles of inclination. 7 v i The grinding wheel shroud is arranged around the rear portion'o'f the wheel and is provided witha large size suction pipe 28 leading to a suction pump29 towithdraw the oil and air mist produced as the jet contacts the.

ing wheel. This movement may be produced by a small motor 31 driving a gear 32 which engages a rack portion 33 attached to the conduit 22. The stroke of the conduit 22 may be controlled by limit switches 34 and 35 attached to the support 24. The switches are alter.- n-a-t ely engagedby a projection or. arm 36,0n the conduit- 22, this arm operating to reverse the motor when the jet reaches the lateral extremes of the grinding wheel cutting surface. The speed of movement of the jet across the surface of the grinding wheel may be of the order of .a small fractional part of a foot per second.

The limit switches may be adjustably located on the support 24 to accommodate grinding'whecls of different widths and the support may be adjusted on the base to compensate for grinding wheel wear and use of diff-erent size wheels. a

The size of the orifice and the pressure of oil supplied to. the orifice are such as tofproduce. a cleaning-action on the cutting surface'of the grinding wheel to maintain it free of loading when the grinding wheel is used on the. kinds of metals ordinarily encountered in machine shop usage. The jetas it emits from the orifice located at a point remote from-the grinding zone is a size of the order of 5 of an inch as previously. described and the pressures of the oil supplied tothe jet orifice, as. previously mentioned, are'very high thereby producing a jet of high velocity so that even with a single jet adequate cleaningis provided. Even though. the pres sures. are very high the amount of cleaning oil supplied isnot excessive and the oil and air mist caused by the. jet can be effectively withdrawn through the suction pipe thereby returning the cleaning oil to the tank.

While. the form of apparatus herein described 'cona stitutes apreferred embodiment of the invention it is to. be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the.

invention which is defined in the appended claims.

What is claimed is:

1.'A cleaning apparatus for cleaning metal loading from a rotating-grinding wheel applied in grinding a dea.

sired contour in a metallic workpiece comprising,

'a supply reservoir containing a grinding wheel coolant a second supply system for pumping said liquid from, Saidreservoir to. a point remote from the grinding zone at high pressure comprising,

range of 4,000 to 20,000pounds per square inch to cause a high velocity jet of low volume to ejectfrorn saidorifi e, supporting means to hold said orifice in close proximity tothe forming surface of the grind-.

ing ,wheel and directed there-against thereby fcrcingsaid liquid into the/grinding wheel,

I meansfor. moving said orifice across the forming.

surface of the grinding wheeldu ring grinding V to thereby clean ilZIOf metal loading,

filter means in said supply conduit upstream of said orifice for preventing obstruction-thereof, and suction. means for collecting the cleaning liquid mist formed by the jet contacting the. grinding wheeland returningsaid liquid to said reservoir, whereby through the continuous remoyal'of metal loading 7 during grinding morev efiicie-nt andprecise forming of metal contours is achieved.

2-. A cleaning apparatus for cleaning loading froma .rota-ting grinding wheelf applied :in grinding a desired-contour in a metallic workpiece comprising, 7

a supply-reservoir containing a grinding wheel coolant liquid for cleaning and cooling, a first pumping system for supplying said from saidv reservoir tothe grinding zone,

means for returning said cooling liquid to said supply reservoir;

1 asecond supply system for pumping said'liq'uidj from said; reservoir to .a point generally180 degrees from the grinding zone at high pressure comprising,

a supply conduit havingan outlet orifice with; an effective outlet diameter ofthe order of of an inch, 7 a i pumping means'forsupplyingsaid liquid through said orificefrat high pressures generally Within a range of 4,000 to 20,000 pounds per square inchto cause a high velocity jet'of lowvolume to eject from said orifice, r supporting means to. hold said orifice in close proximity to the forming surface of the grinding whee1- and directed thereagainst. thereby forcing said liquid into. the. grinding wheel, means for moving said orifice-acrosstheforming surface of thegflndingwheel during grinding to thereby clean it of metal loading,

saidorifice for. preventing obstruction. thereof,

and suction means for'collecting-the cleaning liquid 7 mist'formed hy the, jet contacting the grinding wheel and returning said liquid to said reservoir, whereby.

through the continuous removal .of metal loading during grinding: more efiicient and precise forming of metal contours .is achieved.

3. A cleaning apparatus for cleaning-metal loading from a rotating grinding wheel applied in grinding a desired contour in a metallic workpiece comprising,

a supply reservoir containinga grinding wheel coolant liquid for cleaningand cooling, a first pump meanes having its inlet in communication with said reservoir for supplying cooling liquid from said reservoir to the grinding zone,

first conduit means connected to the discharge of first pump means and having a coolant outlet at a fluid discharge point at the grinding zone .forcoolant flow on both workpiece and-wheel,

a cleaning system-for ejecting liquid from said reser! voir-against the grinding Wheel at a 'pointremote from the grinding zone'at high pressure comprising,

a first cleaning liquid conduit having an outlet orifice with an effective outlet diameterof'the order of 3 of an inch, a

cooling l quid filter: means in'said supply'cond-uit upstream of said a second pump means having its inlet in communication with said reservoir and its discharge connected to said first cleaning liquid conduit for supplying said liquid through said orifice at high pressure generally in excess of 4,000 pounds per square inch .to cause a high velocity jet of low volume to eject from said orifice,

supporting means to hold said orifice in close proximity to the forming surface of the grinding wheel at a location therealong remote from the grinding zone for directing said cleaning liquid solely against said grinding wheel for removing metal loading therefrom and driving said liquid into interstices of said wheel for emission therefrom at the grinding zone to reduce grinding temperatures and inhibit metal loading,

filter means upstream of said orifice for preventing obstruction thereof,

and sump and shroud means for collecting, and conduit means for returning the liquid supplied for cleaning and cooling to said reservoir, whereby through the continuous removal of metal loading and inhibiting thereof during grinding more er'licient and precise forming of metal contours is achieved.

4. A cleaning apparatus for cleaning metal loading from a rotating grinding wheel applied in grinding a desired contour in a metallic workpiece comprising,

a supply reservoir containing a grinding wheel coolant liquid for cleaning and cooling, :1 first pump means having its inlet in communication with said reservoir for supp-lying cooling liquid from said reservoir to the grinding zone,

first conduit means connected to the discharge of said first pump means and having a coolant outlet at a fluid discharge point at the grinding zone for coolant fiow on both workpiece and wheel,

a cleaning system for ejecting liquid from said reservoir against the grinding wheel at a point remote from the grinding zone at high pressure comprising,

a first cleaning liquid conduit having an outlet orifice with an effective outlet diameter of the order of of an inch,

a second pump means having its inlet in comr" 9 munication with said reservoir and its discharge connected to said first cleaning liquid conduit for supplying said liquid through said orifice at high pressure generally in excess of 4,000 pounds per square inch to cause a high velocity jet of low volume to eject from said orifice, supporting means to hold said orifice in close proximity to the forming surface of the grinding Wheel at a location therealong remote from the grinding zone for directing said cleaning liquid solely against said grinding wheel for removing metal loading therefrom and driving said liquid into interstices of said Wheel for emission therefrom at the grinding zone to reduce grinding temperatures and inhibit metal loading, filter means upstream of said orifice for preventing obstruction thereof, means for moving said orifice across the forming surface of the grinding wheel during grinding, and sump and shroud means for collecting, and conduit means for returning the liquid supplied for cleaning and cooling to said reservoir, whereby through the continuous removal of metal loading and inhibiting thereof during grinding more efficient and precise forming of metal contours is achieved.

References Cited in the file of this patent UNITED STATES PATENTS 1,413,060 Roberts Apr. 18, 1922 2,080,206 Holmboe May 11, 1937 2,140,838 Hart Dec. 20, 1938 2,337,018 Hillix et a1 Dec. 14, 1943 2,434,679 Wagner et a1. Jan. 20, 1948 2,475,811 Wagner et al. July 12, 1949 2,555,237 MacPherson May 29, 1951 2,677,219 Burt May 4, 1954 2,694,888 Hill Nov. 23, 1954 2,815,435 Adcock Dec. 3, 1957 2,899,781 Williams Aug. 18, 1959 FOREIGN PATENTS 199,968 Canada May 11, 1920 701,220 Germany Ian. 11, 1941 

1. A CLEANING APPARATUS FOR CLEANING METAL LOADING FROM A ROTATING GRINDING WHEEL APPLIED IN GRINDING A DESIRED CONTOUR IN A METALLIC WORKPIECE COMPRISING, A SUPPLY RESERVOIR CONTAINING A GRINDING WHEEL COOLANT LIQUID FOR CLEANING AND COOLING, A FIRST PUMPING SYSTEM FOR SUPPLYING SAID COOLING LIQUID FROM SAID RESERVOIR TO THE GRINDING ZONE, MEANS FOR RETURNING SAID COOLING LIQUID TO SAID SUPPLY RESERVOIR, A SECOND SUPPLY SYSTEM FOR PUMPING SAID LIQUID FROM SAID RESERVOIR TO A POINT REMOTE FROM THE GRINDING ZONE AT HIGH PRESSURE COMPRISING A SUPPLY CONDUIT HAVING AN OUTLET ORIFICE WITH AN EFFECTIVE OUTLET DIAMETER OF THE ORDER OF 1/100 OF AN INCH, PUMPING MEANS FOR SUPPLYING SAID LIQUID THROUGH SAID ORIFICE AT HIGH PRESSURES GENERALLY WITHIN A RANGE OF 4,000 TO 20,000 POUNDS PER SQUARE INCH TO CAUSE A HIGH VELOCITY JET OF LOW VOLUME TO EJECT FROM SAID ORIFICE, SUPPORTING MEANS TO HOLD SAID ORIFICE IN CLOSE PROXIMITY TO THE FORMING SURFACE OF THE GRINDING WHEEL AND DIRECTED THEREAGAINST THEREBY FORCING SAID LIQUID INTO THE GRINDING WHEEL, MEANS FOR MOVING SAID ORIFICE ACROSS THE FORMING SURFACE OF THE GRINDING WHEEL DURING GRINDING TO THEREBY CLEAN IT OF METAL LOADING, FILTER MEANS IN SAID SUPPLY CONDUIT UPSTREAM OF SAID ORIFICE FOR PREVENTING OBSTRUCTION THEREOF, SAID SUCTION MEANS FOR COLLECTING THE CLEANING LIQUID MIST FORMED BY THE JET CONTACTING THE GRINDING WHEEL AND RETURNING SAID LIQUID TO SAID RESERVOIR, WHEREBY THROUGH THE CONTINUOUS REMOVAL OF METAL LOADING DURING GRINDING MORE EFFICIENT AND PRECISE FORMING OF METAL CONTOURS IS ACHIEVED. 